Laminate web comprising an apertured layer and method for manufacturing thereof

ABSTRACT

A laminate web comprising a first web, a second web joined to the first web at a plurality of discrete bond sites; and a third material disposed between at least a portion of the first and second nonwovens. The third material is apertured in regions adjacent the bond sites, such that the first and second nonwoven webs are joined through the apertures. In one embodiment an apertured laminate web is disclosed, having a first extensible web having a first elongation to break, and a second extensible web joined to the first extensible web at a plurality of bond sites, the second extensible web having elongation to break. A third web material is disposed between the first and second nonwovens, the third web material having a third elongation to break which is less than both of the first or second elongations to break. In a further embodiment, an apertured laminate web is disclosed, having first and second extensible webs being joined at a plurality of discrete bond sites and a third material disposed between the first and second nonwoven webs. The first and second nonwoven webs are in fluid communication via the apertures and have distinct regions being differentiated by at least one property selected from the group consisting of basis weight, fiber orientation, thickness, and density.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. Ser. No.09/584,676, filed on May 31, 2000 now abandoned in the names of Curro etal., which is a continuation-in-part of U.S. Ser. No. 09/467,938, filedon Dec. 21, 1999, now U.S. Pat. No. 6,884,494, issued on Apr. 26, 2005,in the names of Curro et al.

FIELD OF THE INVENTION

This invention relates to a multilayer laminate web, and moreparticularly to a laminate web wherein at least a central layer isapertured. In some embodiments the entire multilayer laminate web isapertured.

BACKGROUND OF THE INVENTION

Laminate webs formed by the joining of discrete webs in a layeredrelationship are well known in the art. For example, often laminatenonwoven webs are utilized in disposable absorbent articles such asdiapers and adult incontinence products. Such laminated webs can be usedas a topsheet, backsheet, or side panels. One example of a laminate webis a film/nonwoven laminate useful for a stretch side panel of adisposable diaper. Nonwoven/nonwoven laminates are also utilized toprovide additional bulk or softness to a web component. Likewise,film/film laminate webs can provide benefits by combining thecharacteristics of various films in a layered relationship. Laminatewebs can also be called composite webs.

Less common examples of laminate webs include laminates of dissimilarmaterials. The materials may be dissimilar in mechanical tensileproperties, thermal properties, or visual/tactile properties. Forexample, a nonwoven web may be joined to a relatively stiff fabric toprovide for a soft surface feel to the fabric. The dissimilar materialsmay be joined by melt bonding, adhesive bonding, ultrasonic bonding, andthe like. Bonding methods are often determined by the materialsthemselves, but often require adhesive bonding. For example, a laminateor composite of materials having widely differing melt properties mayrequire an adhesive layer between laminate layers. Even materials havingsimilar melt properties, such as nonwoven and thermoplastic filmmaterials are often joined by adhesive for adequate bonding to preventunwanted delamination. Although adhesive may be necessary, suchprocessing methods can be expensive due to the addition of adhesive, andthe resulting laminate is often relatively stiff, depending on thelaminate materials and the level of adhesive added.

Often laminate webs are intended to combine properties of theconstituent layers to achieve synergistic benefits. For example,EP-B-715,571 issued to Wadsworth discloses a multilayered nonwovencomposite web intended for use as a substitute for a woven web such as atextile web. The web comprises at least a layer of thermoplasticman-made fibers and a layer of cellulose-based fibers. Thecellulose-based fiber layer is disclosed as thermally bonded to thethermoplastic man-made fiber layers at spaced apart locations. However,it appears that thermal bonding between both, or all, the layers isnecessary to produce the requisite bonding.

EP-A-112,654 issued to Haq, et al. discloses a laminate comprising twosheets of nonwoven fabric or the like having sandwiched between them asolid core material which may be a highly porous, optionallyliquid-containing, polymer. The two outer sheets are bonded to eachother, without involving the core material, by means of a plurality ofsmall, spaced bonding points, for example, spot-welds. Preferably thecore material is in continuous sheet form and is perforated toaccommodate the bonding points. However, it appears it would present asignificant processing problem to register the perforations of the corematerial in order to have the outer layers bonded therethrough.

For many purposes it is desirable to have an apertured nonwoven web, theapertured web being characterized by a plurality of openings, orperforations, in the web. Such apertures can provide for an open meshappearance, as well as beneficial texture and cloth-like properties.Such apertured nonwoven webs can be made by methods known in the art.For example, EP-B-164,740 issued to Shimalla discloses an aperturednon-woven fabric comprising a web of thermoplastic fibers is described.The fabric is formed with a multiplicity of fused patterned regions andadjacent substantially non-fused regions, there being apertures formedwithin a plurality of the fused patterned regions but not within theadjacent regions. The fabric is produced by heat embossing a non-wovenweb of thermoplastic fibers at a temperature above the softening pointof the fibers whereby the regions of the web compressed by theprojections of the embossing means become fused, and immediatelythereafter drafting the embossed web so that apertures are formed in thefused patterned regions. However, it is not apparent that the methoddisclosed would produce a laminate of nonwoven webs, or a laminate ofdissimilar materials.

Another beneficial method of aperturing a nonwoven web, includinglaminates of nonwoven webs is disclosed in EP-A-852,483, issued toBenson et al. Disclosed is a laminate material having, for example, atleast one layer of a spunbonded web joined to at least one layer of ameltblown web, a bonded carded web, or other suitable material. Suchapertured webs are useful as the topsheet in a disposable absorbentarticle. However, this disclosure does not teach laminating webscomprising dissimilar materials (e.g., materials of different materialclasses or having differing material properties).

A perforated multilayer elastic coversheet comprising an intermediateelastic layer between upper and lower nonwoven layers is disclosed inEP-A-784,461 issued to Palumbo. The upper and lower layers are connectedto the intermediate layer only around the perimeters of theperforations. While providing an apertured, elastic laminate, it is notapparent that the method disclosed could produce laminates comprisingthermally-dissimilar materials.

As mentioned, nonwoven webs are beneficial as components of disposableconsumer products, such as diapers, incontinence briefs, training pants,feminine hygiene garments, and the like, as well as in wipes such asdisposable wet wipesHowever, used alone, such nonwovens are limited inthe range of beneficial properties, including visual, tactile, strengthor absorbent properties due to the limits of known methods of making,particularly as compared to woven or knitted materials. Importantly,laminates of nonwoven webs and other materials for use in disposableconsumer products have heretofore been limited due to processinglimitations, including incompatible materials (e.g., thermallydissimilar materials), cost considerations (e.g., adhesive laminationcosts) or tactile properties (e.g., softness and visual aesthetics).

Nonwovens are also beneficial components of other consumer products,such as non-absorbent disposable garments, durable garments, automotivecomponents, upholstered furniture, filtration media, and other consumeror commercial goods. Nonwovens used in these and other applicationsbenefit from their wide range of visual and tactile properties. However,in many cases, the nonwovens used could benefit from being combined withother dissimilar materials in a composite web.

Accordingly, it would be desirable to have laminate webs of dissimilarmaterial properties which are not dependent upon thermal compatibilityof each constituent layer for structural integrity.

Additionally, it would desirable to have a laminate web comprisingnonwoven webs and component webs of different material properties.

Additionally, it would be desirable to have a laminate web formed byjoining the constituent layers without adhesive.

Further, it would be desirable to have an apertured laminate web havingvisually distinct regions giving a fabric-like or knit-like look andfeel.

BRIEF SUMMARY OF THE INVENTION

A laminate web is disclosed, the laminate web comprising a first web, asecond web joined to the first web at a plurality of discrete bondsites; and a third material disposed between at least a portion of thefirst and second nonwovens. The third material is apertured in regionsadjacent the bond sites, such that the first and second nonwoven websare joined through the apertures.

In one embodiment an apertured laminate web is disclosed, having a firstextensible web having a first elongation to break, and a secondextensible web joined to the first extensible web at a plurality of bondsites, the second extensible web having a second elongation to break Athird web material is disposed between the first and second nonwovens,the third web material having a third elongation to break which is lessthan both of the first or second elongations to break.

In a further embodiment, an apertured laminate web is disclose, havingfirst and second extensible webs being joined at a plurality of discretebond sites and a third material disposed between the first and secondnonwoven webs. The first and second nonwoven webs are in fluidcommunication via the apertures and have distinct regions beingdifferentiated by at least one property selected from the groupconsisting of basis weight, fiber orientation, thickness, and density.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims pointing out anddistinctly claiming the present invention, it is believed the same willbe better understood by the following drawings taken in conjunction withthe accompanying specification wherein like components are given thesame reference number.

FIG. 1 is a perspective of one embodiment of a laminate web of thepresent invention.

FIG. 2 is a cross-sectional view of a portion of the laminate web shownin FIG. 1.

FIG. 3 is a magnified detail view of one bond site of a laminate web ofthe present invention.

FIG. 4 is a top plan view of another embodiment of the laminate web ofthe present invention.

FIG. 5 is a cross-sectional view of a portion of the laminate web shownin FIG. 4.

FIG. 6 is a top plan view of another embodiment of the laminate web ofthe present invention.

FIG. 7 is a cross-sectional view of a portion of the laminate web shownin FIG. 6.

FIG. 8 is a photomicrograph of one embodiment of a laminate web of thepresent invention.

FIG. 9 is a schematic representation of a process for making a laminateweb of the present invention.

FIG. 10 is a perspective view of a melt bond calendaring apparatus.

FIG. 11 is a schematic representation of a pattern for the protuberancesof the calendaring roll.

FIG. 12 is a perspective view of an apparatus for stretching a laminateof the present invention to form apertures therein.

FIG. 13 is a cross-sectional view of a portion of the mating portions ofthe apparatus shown in FIG. 12.

FIG. 14 is a perspective view of an alternative apparatus for stretchinga laminate of the present invention in the cross-machine direction toform apertures therein.

FIG. 15 is a perspective view of another alternative apparatus forstretching a laminate of the present invention in the machine directionto form apertures therein.

FIG. 16 is a perspective representation of an apparatus for stretching alaminate of the present invention in both the cross-machine and machinedirections to form apertures therein.

FIG. 17 is a perspective view of a disposable absorbent article havingcomponents that can be made of laminate web material of the presentinvention.

FIGS. 18 A-B are cross-sectional photographs of a bond site before andafter the tensioning step to form an aperture.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “absorbent article” refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term “disposable” is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A“unitary” absorbent article refers to absorbent articles which areformed of separate parts united together to form a coordinated entity sothat they do not require separate manipulative parts like a separateholder and liner.

As used herein, the term “nonwoven web” is used in its plain meaning asunderstood in the art and refers to a web that has a structure ofindividual fibers or threads which are interlaid, but not in anyregular, repeating manner. Nonwoven webs have been, in the past, formedby a variety of processes, such as, for example, meltblowing processes,spunbonding processes and bonded carded web processes.

As used herein, the term “microfibers”, refers to small diameter fibershaving an average diameter not greater than about 100 microns.

As used herein, the term “meltblown fibers”, refers to fibers formed byextruding a molten thermoplastic material through a plurality of fine,usually circular, die capillaries as molten threads or filaments into ahigh velocity gas (e.g., air) stream which attenuates the filaments ofmolten thermoplastic material to reduce their diameter, which may be toa microfiber diameter. Thereafter, the meltblown fibers are carried bythe high velocity gas stream and are deposited on a collecting surfaceto form a web of randomly dispersed meltblown fibers.

As used herein, the term “spunbonded fibers”, refers to small diameterfibers which are formed by extruding a molten thermoplastic material asfilaments from a plurality of fine, usually circular, capillaries of aspinneret with the diameter of the extruded filaments then being rapidlyreduced by drawing.

As used herein, the term “unitary web” refers to a layered webcomprising two or more webs of material, including nonwoven webs, thatare sufficiently joined, such as by thermal bonding means, to behandled, processed, or otherwise utilized, as a single web.

As used herein, “laminate” and “composite” when used to describe webs ofthe present invention, are synonymous. Both refer to a web structurecomprising at least two webs joined in a face to face relationship toform a multiple-layer unitary web.

As used herein, the term “polymer” generally includes, but is notlimited to, homopolymers, copolymers, such as, for example, block,graft, random and alternating copolymers, terpolymers, etc., and blendsand modifications thereof. Furthermore, unless otherwise specificallylimited, the term “polymer” shall include all possible geometricalconfigurations of the material. These configurations include, but arenot limited to, isotactic, syndiaotactic and random symmetries.

As used herein, the term “elastic” refers to any material which, uponapplication of a biasing force, is stretchable, that is, elongatable, atleast about 60 percent (i.e., to a stretched, biased length, which is atleast about 160 percent of its relaxed unbiased length), and which, willrecover at least 55 percent of its elongation upon release of thestretching, elongation force. A hypothetical example would be a one (1)inch sample of a material which is elongatable to at least 1.60 inches,and which, upon being elongated to 1.60 inches and released, willrecover to a length of not more than 1.27 inches.

Many elastic materials may be elongated by more than 60 percent (i.e.,much more than 160 percent of their relaxed length), for example,elongated 100 percent or more, and many of these materials will recoverto substantially their initial relaxed length, for example, to within105 percent of their initial relaxed length, upon release of the stretchforce. Such materials are denoted herein by the term “highly elastic”which refers to any material which upon application of a biasing force,is stretchable, that is, elongatable, at least about 200 percent (i.e.,to a stretched, biased length, which is at least about 300 percent ofits relaxed unbiased length), and which, will to within 105 percent oftheir initial relaxed length, upon release of the stretch force.Therefore, highly elastic materials are generally also elastic, but notall elastic materials are highly elastic.

As used herein, the term “nonelastic” refers to any material which doesnot fall within the definition of “elastic” above.

As used herein, the term “extensible” refers to any material which, uponapplication of a biasing force, is elongatable, at least about 25percent without experiencing catastrophic failure. Catastrophic failureincludes substantial tearing, fracturing, rupturing, or other failure intension such that, if tested in a standard tensile tester, the failurewould result in a sudden significant reduction in tensile force. As usedherein, the term “highly extensible” refers to any material which, uponapplication of a biasing force, is elongatable, at least about 100percent without experiencing catastrophic failure.

The Laminate Web

The laminate web 10 of the present invention comprises at least threelayers or plies, disposed in a layered, face-to-face relationship, asshown in FIG. 1. The layers should be sufficiently thin to beprocessible as described herein, but no actual thickness (i.e., caliper)is considered limiting. A first outer layer 20, is preferably thermallybondable, and is preferably a nonwoven web comprising a sufficientquantity of thermoplastic material, the web having a predeterminedextensibility and elongation to break. By “sufficient quantity” is meanta quantity of thermoplastic material adequate to enable enough thermalbonding upon application of heat and/or pressure to produce a unitaryweb. A second outer layer, 40, is preferably the same material as firstouter layer 20, but may be a different material, also being thermallybondable and having a predetermined extensibility and elongation tobreak. At least one third central layer 30 is disposed between the twoouter layers. The laminate web 10 is processed by joining means, such asby ultrasonic welding, or thermal calendaring as described below toprovide a plurality of melt bond sites 50 that serve to couple the outerlayers 20 and 40, and, in some embodiments, portions of central layer30, thereby forming the constituent layers into a unitary web. Whenjoined together, the two outer layers form an interior region betweenthem. The interior region is the space between the outer layerssurrounding the bond sites 50. In a preferred embodiment, the thirdcentral layer 30 substantially fills the interior region, the thirdcentral layer 30 being apertured coincident the bond sites 50.

While the laminate web 10 is disclosed primarily in the context ofnonwoven webs and composites, in principle the laminate web 10 can bemade out of any web materials that meet the requirements, (e.g., meltproperties, extensibility) as disclosed herein. For example, the outerlayers 20 and 40 can be thermoplastic films, micro-porous films,apertured films, and the like. Central layer 30 can be paper, includingtissue paper; metal, including metal foil; other non-thermoplastic webmaterial, woven fabric, and the like. In general, it is required thatouter layer materials be flexible enough to be processed as describedherein. However, central layer can be a brittle, relatively stiffmaterial, as long at it also can be processed as described herein,albeit possibly becoming fractured, broken, or otherwise broken up inthe process. One of the unexpected advantages of the present invention,therefore, is the discovery that novel web properties can be exhibitedby the choice of central layer 30 disposed between the two outer layers.

Non-apertured Embodiment

In one embodiment, as shown in cross-section in FIG. 2, central layer 30can be apertured, without aperturing the two outer layers to provide athree-layer laminate characterized by the laminate web 10 (as a whole)being un-apertured, while the central layer 30 is apertured.Importantly, the web of the present invention can be made by the methodof the present invention without requiring registration of the layers toensure bonding of the outer layers through the apertures of the centrallayer(s). One way of describing a preferred embodiment of a web 10 asdescribed above, is that the unitary web 10, when viewed orthogonally bythe un-aided human eye from a distance of approximately 50 cm, exhibitsno apertures or perforations through the entire laminate, but bond sites50 are nevertheless visible.

The laminate web 10 is further characterized in that the joining of thethree plies into a unitary web can be achieved in the absence ofadhesive. That is, in certain preferred embodiments no adhesive isrequired to bond the plies together; joining is achieved by the input ofenergy into the constituent layers, such as by thermal melt bonding ofthe two outer layers together at the melt bond sites 50. In otherembodiments, the energy input can be via ultrasonic bonding.Accordingly, a significant benefit of the present invention is theprovision of a laminate web, that is a unitary web, formed without theuse of adhesives. Not only does this simplify processing and lower thecost of the laminate web, when certain materials such as nonwoven websare used, it results in a more flexible, softer web.

As shown in FIG. 2, central layer 30 is chosen such that when theconstituent web layers of laminate web 10 are processed by the method ofthe present invention, portions of central layer 30 in the region of themelt bond sites 50 separate to permit the first outer layer 20 to meltbond directly to the second outer layer 40 at the interface of the twomaterials 52 at melt bond sites 50. Thus, apertures in the central layer30 are formed in the lamination step by displacement, just prior to thebonding of the outer layers as detailed by the method of the presentinvention below. In this manner, central layer 30 can be provided as anunapertured web, avoiding complex registration steps to align aperturesin registry with bond sites when laminated. Further, central layer 30need not be thermally compatible with outer layers 20 and 40. Centrallayer need not be a thermoplastic material, and need not even have amelting point. It simply needs to be displaceable by the forces exertedby the processing equipment as detailed below. Therefore, one way ofdescribing the laminate web of the present invention is to distinguishthe central layer as being a material differentiated from the materialsof the first or second layers by at least one material property selectedfrom thermal properties, elongation properties, elastic properties, orconductive properties. By “thermal properties” is meant primarilythermal melt properties, such that the central layer has no meltingpoint, or if it has a melting point, it is preferably at least about 10degrees Centigrade higher, more preferably about 20 degrees Centigradehigher than either outer layer, and can be 100 degrees Centigrade higherthan either outer layer. By “elongation properties” is meant that intension, the material of the central layer exhibits an elongation tobreak that is at least 10% less than either outer layer, more preferably50% less than either outer layer, and can be greater than 100% less thaneither outer layer. Thus, the central layer can be extensible, whileeither outer layer can be highly extensible. By “elastic properties” ismeant that the central layer can be, for example, elastic, while eitherouter layer can be highly elastic, as defined herein. Or the centrallayer can be non-elastic, and the outer layers elastic or highlyelastic. By “conductive properties” as used herein is meant electricallyconductivity, such that the central layer can have an electricalconductivity that is 10 times, and more preferably 100 or more times asgreat as the outer layers. Conductive properties may be facilitated bythe central layer being a metallic foil, or by being a conductivepolymer, including a conductive nonwoven web.

Another advantage of the method of the present invention is that, insome embodiments, e.g., for solid core central layer 30 materials (i.e.,a continuous sheet, that is, not having substantial apertures, gaps, orother voids), it results in a unitary web having an apertured centrallayer 30 in full, intimate contact with the outer layers 20, and 40. By“full” and “intimate” is meant that central layer 30 fills all theunbonded regions between outer layers 20 and 40 such that outer layers20 and 40 do not contact except at the bond sites 50. Of course, it isrecognized that many materials of interest have significant air content,and filling “all” the unbonded region between outer layers 20 and 40 isnot meant to imply that all air content is removed.

Central layer 30 can be involved, or participate, in the bonding betweenouter layers 20 and 40. By “involved” is meant that the central layercan, to some extent, be in intimate contact with, and possibly partiallymerged with, one or both immediate outer layers. The involvement may bedue to actual melt bonding about the perimeter of bond site 50 (e.g.,for thermoplastic central layers 30), or it may be due to mechanicalinteraction, such as by entanglement (e.g., for cellulosic fibrouscentral layer 30 between fibrous nonwoven layers), also about theperimeter of bond site 50. For example, FIG. 18-A shows in cross-sectiona unitary web comprising two outer nonwoven layers and a cellulosictissue paper central layer. As can be seen, the lighter-colored centrallayer, due to the process of being “squeezed” apart, is intimatelyinvolved with the two outer layers at the bond site.

Without being bound by theory, it is believed that the process of thepresent invention facilitates such separation of central layer 30 byshearing, cutting, or otherwise fracturing the central layer 30, anddisplacing the material of the central layer 30 sufficiently to permitthermal bonding of the two outer layers 20 and 40. Thus, central layer30 must be chosen to have properties that permit such displacement.Therefore, central layer 30 should have one or more of the properties ofrelatively low extensibility, relatively high frangibility, orrelatively high deformability, such that the material of central layer30 can be “squeezed” or otherwise displaced out of the region of thermalbond sites 50. Importantly, it is not required that the central layer 30be melted out of the region of the thermal bond sites. Thus, centrallayer can be elastic, highly elastic, extensible, or highly extensible,depending on the desired end results and purposes of the resultingunitary web.

Without being bound by theory, it is believed that to accomplish thedisplacement of central layer 30 to form apertures therein and to bondthe outer layers, the thermal point calendaring described below shouldform thermal bond sites having a narrow width W dimension and a highaspect ratio. For example, FIG. 3 shows the melt area of a single meltbond site 50 having a narrow width dimension W and a high aspect ratio,i.e., the length, L, is much greater than the width, W. The length Lshould be selected to permit adequate bond area while width W issufficiently narrow such that the protuberance used to form the bondsite (as described below) can cut, shear, displace, or otherwise piercethe central layer 30 at the region of the bond sites by the methoddescribed below. Width W can be between about 0.003 inches and 0.020inches, but in a preferred embodiment, is between about 0.005 inches and0.010 inches, and may be adjusted depending on the properties of centrallayer 30.

It is believed that the aspect ratio of melt bond site 50 can be as lowas about 3 (i.e., ratio of L/W equals 3/1). It can also be between about4 and 20. In one preferred embodiment, the aspect ratio was about 10. Itis believed that the aspect ratio of the melt bond sites 50 is limitedonly by the corresponding aspect ratio of the point bondingprotuberances of the calendaring roller(s), as detailed below.

In a preferred embodiment, the longitudinal axis of each bond site, 1,which corresponds directionally to the length dimension of bond site 50,is disposed in a regular, repeating pattern oriented generally parallelto the machine direction, MD as shown in FIG. 1. But the longitudinalaxis of each bond site may be disposed in a regular, repeating patternoriented in the cross machine direction, or randomly oriented in amixture of cross and machine directions. For example, the bond sites 50can be disposed in a “herringbone” pattern.

When nonwoven webs are used as constituent layers of laminate 10, animportant distinction should be drawn between bond sites 50 which bondtogether outer layers 20 and 40 by the method of the present invention,and thermal bond sites that may be present in the constituent layersthemselves. For example, nonwoven webs are typically consolidated bythermal bonding in a regular pattern of discrete spaced apart fusedbonding areas, such as the pattern disclosed in U.S. Pat. No. 3,855,046to Hansen et al., and the patterns shown generally in FIGS. 10 and 11 ofU.S. Pat. No. 5,620,779 to Levy et al. Other films, nonwoven webs, andthe like may have thermal embossments for aesthetic reasons. Therefore,in the unitary web 10 there may be many thermal bond sites, some ofwhich are bond sites 50, and others which are bond sites in the basenonwoven, for example.

The bond sites of the base nonwoven do not typically have an aspectratio greater than about 1, so that these bonds do not typically formapertures in the constituent layer during the stretching step disclosedbelow. Also, the spacing of such bond sites is typically a repeatingpattern of bonded and unbonded area which may or may not provide formachine direction (MD) columns of bonded area next to columns ofunbonded area. After forming bond sites 50, however, there is not likelyto be any significant MD columns of unbonded areas; the overall bondpattern of any constituent nonwoven fabric is a combination of existingbonded areas and bond sites 50. Together the two sets of bond sitesresult in a complex pattern of bond sites that may or may not bedescribed as columnar, regular, or uniform.

The resulting web of the present invention, as shown in cross-section inFIG. 2, is a laminate web 10 that is itself unapertured, but the centrallayer 30 is apertured coincident the regions of the bond sites 50. Asstated above, by “unapertured” is meant that, on the whole, the laminateweb 10 is considered unapertured. It is recognized that the un-aperturedlaminate web 10 of the present invention may have localized cut through,or tearing at bond sites 50 due to materials and processing variabilityor post lamination handling. Ideally, such cut through of the entire webis minimized and eliminated. Likewise, it is recognized that in someinstances, there may not be complete displacement of the central layer30 at all locations of bond sites 50 such that some localized portionsof central layer 30 may not be apertured (and the outer layers notbonded). Nevertheless, the description herein is made for the laminateweb 50 as a whole, and is not meant to be limited by aberrations oranomalies due to potential material or processing variables.

To produce the webs of the present invention, including as described inFIG. 2, the outer layers should have sufficient elongation to permit thenecessary local deformation in the immediate vicinity of bond sites 50.Thus, the outer layers 20 and 40 can be extensible, highly extensible,elastic, or highly elastic.

The central layer 30 itself need not be thermally compatible with theouter layers. The central layer 30 need not even be melt processible. Itcan be, for example, a cellulosic material, such as paper; a metallicmaterial, such as a metal foil; a woven or knit material, such as cottonor rayon blends; or a thermoset material, such as a polyester oraromatic polyamide film. The central layer 30 can be another nonwovenhaving suitable properties for processing into an apertured layer. Ifcentral layer 30 has a melting point, it is preferably at least about 10degrees Centigrade higher, more preferably about 20 degrees Centigradehigher than the outer layers. In certain embodiments, for example ametal foil central layer 30 between thermoplastic nonwoven outer layers,the central layer can have a melting point at least 100 degreesCentigrade higher than the outer layers. However, central layer 30 neednot have a melting point, and may simply experience softening at thecalendaring temperatures required to bond the laminate. In certaincentral layer materials, such as metal foils, there may not be anysoftening due to thermal processing of the web.

The wide range of possible central layer materials permits a surprisingvariety of structures of the present invention, each having beneficialapplication in a wide assortment of end uses. For example, when outerlayers of nonwoven material are used with a central layer of metal foil,the resulting laminate is a flexible, soft, formable, conductive webthat is relatively quiet when folded, crumpled or otherwise deformed.Such a material can be used in applications requiring electricalshielding, for example. When a central layer of tissue paper is used,the resulting laminate is a soft, bulky, absorbent web. Such a laminateis suitable for use as a wiping implement, for example. Further, sincethe laminate web 10 is formed without the use of thermoplasticadhesives, durable, garment-like properties can be obtained. Suchlaminates can be laundered a number of times before sufferingunacceptable wear.

By way of example, laminate web 10 can be a conductive fabric comprisingrelatively non-conductive thermoplastic outer layers 20 and 40 and arelatively conductive central layer 30. The outer layers can benon-woven webs for a low cost, soft, breathable conductive fabric. Thecentral layer can be a metal foil, such as a copper foil or an aluminumfoil. The central layer can also be a conductive polymer, a non-foilconductive fabric, or a composite conductive material. In general, as aconductive fabric embodiment, the outer layers should serve to insulatethe conductive central layer(s). In a preferred three-layer embodimentthe outer layers each have a first electrical resistance and the centrallayer has a second electrical resistance which is at least one-tenth thefirst electrical resistance, more preferably one-hundredth (i.e., thecentral layer is 10 times, preferably 100 times as conductive as theouter layers).

A conductive laminate web 10 can find use as a sheet of conductivematerial for signal propagation. It can also find use as a shieldingmaterial. In particular, the aspect ratio of the bond sites 50 can bepredetermined for particular shielding characteristics. By altering thelength, width, and orientation of the bond sites 50 certain wavepropagation of electromagnetic waves can be altered or stopped. Forexample, the bond sites 50, which represent penetration of theconductive central layer, can be designed to be effective in filteringcertain wavelengths of electromagnetic radiation. In addition to theelectrical characteristics of such a web, the laminate web 10 can be,and preferably is, very flexible and formable, such that the conductiveor shielding benefits can be applied in a non-planar fashion. Forexample, sensitive electronic equipment can be wrapped with a fabricshield.

A further benefit of the present invention is the capability to combineboth thermoplastic and non-thermoplastic materials without anyadhesives, to provide fabric-like composites having unique physicalproperties. For example, a material having high tensile strength andresistance to tear can include as a central layer 30 TYVEK®, availablefrom DuPont, Wilmington Del., USA. TYVEK®, and equivalent or similarmaterials under other tradenames, is an extremely strong but breathablepolyolefin nonwoven, commonly used as a house-wrap layer. However, it isnot soft and clothlike, but has the look and feel of a plastic film.When used in a laminate web 10 of the present invention, for examplewith nonwoven outer layers, the laminate web exhibits the softness of anonwoven with the strength of the TYVEK® layer. Again, this laminate canbe, and is preferably, made without the use of adhesives to bind the webinto a unitary web.

Further, relatively strong materials such as TYVEK® can be combined withadditional central layers 30 to make laminate webs 10 having a varietyof physical properties. For example, a laminate web comprising a TYVEK®layer can also comprise an absorbent layer, such a layer of absorbenttissue paper, such as BOUNTY® paper towel, available from The Procter &Gamble Co., Cincinnati Ohio, USA and one or more outer layers ofpolyethylene nonwoven (e.g. Corolind, available from BBA, Simpsonville,S.C., USA). Such a composite formed according to the method of thepresent invention can be transformed into a highly textile-likematerial, exhibiting the unusual combined properties of relatively highabsorbency (from the BOUNTY® paper towel layer(s)), and relatively highstrength (from the TYVEK® layer(s)).

Apertured Embodiments

A further benefit of the present invention is obtained when thenon-apertured thermally bonded laminate web described above is stretchedor extended in a direction generally orthogonal to the longitudinalaxis, 1, of melt bond sites 50. The melt bonding at the melt bond sites50 tends to make localized weakened portions of the web at the bondsites. Thus, as portions of the web 10 are extended in a directiongenerally orthogonal to the longitudinal axis I of bond sites 50, thematerial at the bond site fails in tension and an aperture is formed.The relatively high aspect ratio of melt bond sites 50, permits arelatively large aperture to be formed upon sufficient extension. Whenthe laminate web 10 is uniformly tensioned, the result is a regularpattern of a plurality of apertures 60 corresponding to the pattern ofmelt bond sites 50.

FIG. 4 shows a partially cut-away representation of an aperturedlaminate of the present invention. As shown, the partial cut-awaypermits each layer or ply to be viewed in a plan view. The laminate web10 shown in FIG. 4 is produced after the thermally bonded laminate isstretched in a direction orthogonal to the longitudinal axis of the meltbond sites, in this case, in the cross-machine direction, CD withsufficient elongation in the direction of extension to cause aperturesto form. As shown, where formerly were melt bond sites 50, apertures 60are produced as the relatively weak bond sites fail in tension. Also asshown, central layer 30 can remain generally uniformly distributedwithin laminate 10, depending on the material properties of centrallayer 30. For example, if central layer 30 is more extensible than outerlayers 20 or 40, then it simply extends, either elastically or byplastic deformation, but remains generally uniformly distributed in theunapertured regions of web 10. For example, if a thermoplastic film isutilized as the central layer 30, it extends, either extensibly orelastically (depending on the type of film), but can remain generallyuniform, for example, in density or basis weight.

When apertures 60 are formed, the thermally bonded portions of outerlayers 20 and 40 remain primarily on the portions of the apertureperimeters corresponding to the length dimension of bond sites 50.Therefore, each aperture 60 does not have a perimeter of thermallybonded material, but only portions remain bonded, represented as 62 inFIG. 4. One beneficial property of such a laminate web is that onceapertured, fluid communication with the central layer is facilitated.Thus, an absorbent central layer 30 can be used between two relativelynon-absorbent outer layers, and the laminate 10 could be an absorptivewiper with a relatively dry to the touch outer surface.

To the extent that central layer 30 is involved, or participates, in anybonding between outer layers 20 and 40, it also participates in theremnant of bonded portions 62, as shown in FIG. 4. The involvement maybe due to some degree of actual melt bonding about the perimeter of bondsite 50 (e.g., for thermoplastic central layers 30 ), or it may be dueto mechanical interaction, such as by entanglement (e.g., for cellulosicfibrous central layer 30 between fibrous nonwoven layers).

FIG. 5 is a schematic representation of the cross-section denoted inFIG. 4. As shown, apertures 60 form when the laminate web is elongatedin the direction T.

Another benefit of the present invention is obtained when the laminateis extended as described with reference to FIG. 4, but the central layer30 is chosen to have an elongation to break less than either of the twoouter layers, and less than the actual magnitude of extension. Thus,upon extension of the laminate web generally orthogonal to thelongitudinal axis, 1, sufficient to form apertures in outer layers 20and 40 (and thus the entire laminate web 10) central layer 30 fails intension. Therefore, central layer 30 fractures (i.e., fails in tension)upon sufficient extension, such that after extension central layer 30 isno longer uniformly distributed over the non-apertured regions of thelaminate web 10.

An example of one embodiment of a unitary web having a central layerhaving an elongation to break less than either of the two outer layers,and less than the actual magnitude of extension, is shown partiallycut-away in FIG. 5. The partial cut-away permits each layer or ply to beviewed in a plan view. As shown, after extension, central layer 30becomes fragmented, forming discontinuous regions of the central layermaterial. These discontinuous regions may be relatively uniformlydistributed, such as in rows as shown in FIG. 5, or may be relativelyrandomly distributed, depending on the pattern of melt bond sites 50,the physical properties of central layer 30, and the method of extensionemployed.

One example of a web 10 having a structure similar to that shown in FIG.5 is a web having outer layers of relatively extensible nonwovens, witha central layer of relatively low extensibility tissue paper. Such alaminate would be an apertured laminate web having an absorbent centralcore, wherein the absorbent core material is in fluid communication withregions exterior to the laminate web. That is, for example, if such alaminate web comprised nonwoven outer layers, it could be used as anabsorbent wiper. Fluids could thus be absorbed via the apertures, theperimeter of which can be open at portions which provide fluidcommunication to the absorbent central core. If a relatively hydrophobicnonwoven web is used for the outer layers, such a wiper could exhibitdry-to-the-touch properties along with high absorbency.

One example of a web 10 having a structure similar to that shown in FIG.5 is a web having outer layers of relatively extensible nonwovens, witha central layer of relatively low extensibility tissue paper. Oneparticularly interesting structure incorporates a highly hydrophobicouter layer combined with a highly absorbent central layer. A suitablehydrophobic material is described in U.S. Pat. No. 3,354,022 Dettre etal. Such a material has a water repellent surface having an intrinsicadvancing water contact angle of more than 90 degrees and an intrinsicreceding water contact angle of at least 75 degrees. Such a materialexhibits extremely hydrophobic properties, similar to the effect knownto exist on leaves from the Lotus plant. When such a material iscombined with an absorbent central layer, such as a BOUNTY® paper toweltissue layer, the resulting composite can be highly absorbent whileretaining a very clean and dry outer surface. The basis weight andporosity of the outer layer can be varied to achieve different degreesof absorbent performance. In one embodiment the laminate could also bepost-laminated to a fluid-impervious backing layer to form an absorbentfluid barrier. The fluid-impervious backing layer could be a flexiblepolymeric film for use such absorbent articles as sanitary napkins,diapers, place mats, floor mats, protective covers, and the like.

One surprising beneficial characteristic of the laminate web structureof the present invention described with reference to FIG. 6 is thepresence of distinct regions in the non-apertured portion of the webbeing differentiated by at least one property selected from the groupconsisting of basis weight, thickness, or density. As shown in thecross-section of FIG. 7, several such regions can be differentiated. Ina preferred embodiment, the regions are visually distinct, giving thelaminate an aesthetically pleasing look and feel. The regions may alsogive the laminate a garment-like or knit-like texture and hand.

With reference to FIG. 7, several structurally distinct regions can beidentified in the cross-section shown. The region denoted 64 correspondsto the aperture 60. In the non-apertured area of the web, a region 66 isa relatively high basis weight region comprising central layer 30.Region 68 represents the portion of the laminate web in which centrallayer 30 has fractured and separated, i.e., is no longer fully present,forming a relatively low basis weight region of web 10. In general, thehigher basis weight regions will also be correspondingly higher densityregions, but need not be so. For example, a post-extension embossingprocess can be applied to web 10 to form regions of multiple densitiesin addition to the regions of multiple basis weight. For either the highbasis weight regions or the high density regions, often the differencescan be discernible by simply rubbing the laminate web between thefingers.

In general, for a laminate web 10 having generally parallel rows of meltbond sites 50 extending in the machine direction MD, whichcorrespondingly form generally parallel rows of apertures when extended,and having a central layer with a lower elongation to break than theouter layers, the resulting extended, apertured laminate web 10 ischaracterized by generally low basis weight, low density regions betweenthe apertures in the machine direction, MD, e.g., region 68 in FIGS. 6and 7. Likewise, such a laminate web 10 is characterized by relativelyhigh basis weight, high density regions between adjacent rows ofapertures in the cross-machine direction, CD, e.g., region 66 in FIG. 7.By choice of central layer material 30 and possibly post laminatingoperations, e.g., an embossing process, the thickness of the laminateweb can likewise be varied, the thicker regions generally correspondingto the higher density regions.

On particularly useful embodiment of a laminate web as described withreference to FIG. 7, is a conductive fabric for signal transmission viaa plurality of closely-spaced, parallel signal conductors. For example,if a conductive metal foil is used as central layer 30, upon sufficientextension in the CD by the incremental stretching operation describedbelow, the metal foil fractures into a plurality of discrete conductiveribbons corresponding to the high basis weight region 66 of FIG. 7.Outer layers 20 and 40 are preferably chosen for their insulatingproperties, and are, therefore, preferably thermoplastic polymericmaterial. For high-speed transmission of electrical signals, alow-dielectric material, such as polytetrafluoroethylene (PTFE), andpreferably expanded PTFE (e.g., GORE-TEX® available from W. L. Gore andAssociates, Newark, Del., USA) can be used as the insulating outerlayers. Additional outer layers can be added (e.g., post laminateformation), including additional conductive layers to form a shieldedribbon cable. Figure X shows an example of such a conductive ribbon . ..

Another embodiment of a laminate web of the present invention utilizingnonwoven webs as the outer layers is characterized by distinct regionsdifferentiated by fiber orientation. Differential fiber orientation canbe achieved by providing for localized regions within the web thatexperience greater extension than other regions. For example, by locallystraining the web 10 to a greater degree in the regions corresponding toregions 68 in FIG. 6, regions of significant fiber reorientation areformed. Such localized straining is possible by the method of thepresent invention detailed below.

FIG. 8 is a photomicrograph showing in magnified detail a web of thepresent invention comprising nonwoven outer layers which has beenextended to form apertures, and locally extended to produce regions 68of fiber reorientation. As can be seen in FIG. 8, by locally extendingportions of the web to a greater extent than others, the aperturesformed thereby can be of different sizes. Thus, the region denotedgenerally as 70 in FIG. 8 has undergone more strain (i.e., localextension) than the region denoted by 72. Thus, the apertures in region70 are larger than those in region 72, and the basis weight of thenonwoven web material in region 72 is less than the basis weight of thenonwoven web in region 70. In addition to the difference in basis weightdue to localized strain differentials, the laminate web of the presentinvention can also exhibit distinct regions 68 of fiber reorientation.In these regions, the fibers have been reoriented from a generallyrandom orientation to a predominant orientation in the direction ofextension.

To make a web 10 as shown in FIG. 6, central layer 30 can be any of agreat number of dissimilar materials. For example, if outer layers 20and 40 are nonwoven webs having a relatively high elongation to break,central layer 30 can be paper, tissue paper, thermoplastic film, metalfoil, closed or open cell foam, or any other material that has arelatively low elongation to break compared to the two outer layers. Theouter layer materials may themselves be dissimilar, with the onlyconstraint being that the central layer be relatively less extensible inthe direction of extension to form apertures.

Additionally, more than one central layer 30 can be used with beneficialresults. For example, a structure comprising a cellulosic tissue centralweb and a polymeric film central web between two nonwoven webs canproduce an absorptive wiping article with one side being relatively moreabsorptive than the other. If the film layer is a three-dimensionalformed film, the film side can provide added texture to the laminatewhich is beneficial in many wiping applications.Macroscopically-expanded, three-dimensional formed films suitable foruse in the present invention include those described incommonly-assigned U.S. Pat. No. 3,929,135 issued to Thompson on Dec. 30,1975, and U.S. Pat. No. 4,342,314 issued to Radel et al. on Aug. 3,1982, both patents hereby incorporated herein by reference.

The (or “a”) central layer can also be elastomeric, and can be anelastomeric macroscopically-expanded, vacuum-formed, three-dimensionalformed film, such as described in commonly-assigned U.S. Ser. No.08/816,106, entitled “Tear Resistant Porous Extensible Web” filed byCurro et al. on Mar. 14, 1997, and hereby incorporated herein byreference. Further, the (or “a”) central layer can be athree-dimensional formed film having micro-apertures such as describedin commonly-assigned U.S. Pat. No. 4,629,643 issued to Curro et al. onDec. 16, 1986, and 4,609,518, issued to Curro et al. on Sep. 2, 1986,both of which are hereby incorporated herein by reference.

The (or “a”) central layer can be a web material having a strainablenetwork as disclosed in U.S. Pat. No. 5,518,801 issued to Chappell etal. on May 21, 1996, and hereby incorporated herein by reference. Such aweb can be a structural elastic-like film (SELF) web, formed by, forexample, embossing by mating plates or rolls.

The (or “a”) central layer can be an absorbent open cell foam webmaterial. Particularly suitable absorbent foams for high performanceabsorbent articles such as diapers have been made from High Internalphase Emulsions (hereafter referred to as “HIPE”). See, for example,U.S. Pat. No. 5,260,345 (DesMarais et al), issued Nov. 9, 1993 and U.S.Pat. No. 5,268,224 (DesMarais et al), issued Dec. 7, 1993, herebyincorporated herein by reference. These absorbent HIPE foams providedesirable fluid handling properties, including: (a) relatively goodwicking and fluid distribution characteristics to transport the imbibedurine or other body fluid away from the initial impingement zone andinto other regions of the foam structure to allow for subsequent gushesof fluid to be accommodated; and (b) a relatively high storage capacitywith a relatively high fluid capacity under load, i.e. under compressiveforces.

The central layer 30 may comprise absorbent gelling materials. Forexample, supersorbers or hydrogel materials may provide for superiorabsorbency when the laminate web of the present invention is used as anabsorbent wipe or an absorbent core in a disposable absorbent article.By “hydrogel” as used herein is meant an inorganic or organic compoundcapable of absorbing aqueous fluids and retaining them under moderatepressures. For good results the hydrogels should be water insoluble.Examples are inorganic materials such as silica gels and organiccompounds such as cross-linked polymers. Cross-linking may be bycovalent, ionic, vander Waals, or hydrogen bonding. Examples of polymersinclude polyacrylamides, polyvinyl alcohol, ethylene maleic anhydridecopolymers, polyvinyl ethers, hydroxypropyl cellulose, carboxymethylcellulose, polyvinyl pyridine and the like.

One benefit of the laminate of the present invention is the ability tomake a laminate structure of dissimilar materials without the use ofadhesive for joining. Because the central layer of the laminate web 10is penetrated by the protuberances of the calendaring roll at melt bondsites, it can comprise non-thermally-bondable materials. The pluralityof melt bond sites 50 are sufficient to keep the component webs togetherin the laminate web, so that the laminate web behaves as a unitary webfor processing integrity and use, without unwanted delamination.However, in some embodiments, and for certain materials, it may bebeneficial to apply adhesive between at least two of the constituentlayers.

The laminate web of the present invention, being bonded by a pluralityof relatively closely spaced thermal bond sites (without the use ofthermoplastic adhesives) can be beneficially used for durable articles.For example, a laminate web of the present invention comprising nonwovenweb outer layers and having a clothlike feel and appearance, can be usedin durable garments. Certain embodiments of the laminate web of thepresent invention can survive repeated washing and drying in householdwashing and drying equipment, depending on the component webs of thelaminate, and the level of thermal bonding. Due to the knit-like orfabric-like look and feel of certain embodiments of the presentinvention, such durability can result in durable garment components suchas interliners and the like.

Method of Making

Referring to FIG. 9 there is schematically illustrated at 100 a processmaking a laminate web of the present invention.

A first web 120 which can be a relatively extensible web, is unwoundfrom a supply roll 104 and travels in a direction indicated by thearrows associated therewith as the supply roll 104 rotates in thedirection indicated by the arrows associated therewith. Likewise asecond web 140, which can be a relatively extensible web is unwound fromsupply roll 105. A central layer 130, which can be a relativelyinextensible layer, is likewise drawn from supply roll 107. The threecomponents (or more, if more than one central layer is used) passthrough a nip 106 of the thermal point bond roller arrangement 108formed by rollers 110 and 112.

In addition to thermoplastic nonwoven materials, either outer layer cancomprise a polymeric film, for example a polyolefinic (e.g., PP or PE)thin film. If the entire outer layer is not uniformly thermoplastic, atleast sufficient amounts to effect melt bonding must be thermoplastic.Conjugate fibers, such as bicomponent fibers can be used in the outerlayers to facilitate thermal bonding of the outer layers. Either outerlayer can comprise a formed film, such as a three-dimensional formedfilm having micro-apertures such as described in commonly-assigned U.S.Pat. No. 4,629,643 issued to Curro et al. on Dec. 16, 1986, and4,609,518, issued to Curro et al. on Sep. 2, 1986, both of which arehereby incorporated herein by reference.

In a preferred embodiment, both outer layers comprise nonwovenmaterials, and may be the identical. The nonwoven material may be formedby known nonwoven extrusion processes, such as, for example, knownmeltblowing processes or known spunbonding processes, and passeddirectly through the nip 106 without first being bonded and/or stored ona supply roll. However, in a preferred embodiment, the nonwoven webs arethemselves thermally point bonded (consolidated) webs commerciallyavailable on supply rolls. The thermal point bonds, which are typicallyin the form of a regular pattern of spaced-apart diamond shaped bondsites, are present in the nonwoven as purchased from a nonwoven vendor,and are to be distinguished in the web of the present invention from thebond sites 50 formed by the method of the present invention.

The nonwoven web outer layer(s) may be elastic, highly elastic ornonelastic. The nonwoven web may be any melt-fusible web, including aspunbonded web, a meltblown web, or a bonded carded web. If the nonwovenweb is a web of meltblown fibers, it may include meltblown microfibers.The nonwoven web may be made of fiber forming polymers such as, forexample, polyolefins. Exemplary polyolefins include one or more ofpolypropylene, polyethylene, ethylene copolymers, propylene copolymers,and butene copolymers. The nonwoven web can have a basis weight betweenabout 10 to about 60 grams per square meter (gsm), and more preferablyabout 15 to about 30 gsm.

The nonwoven web outer layers may themselves be a multilayer materialhaving, for example, at least one layer of a spunbonded web joined to atleast one layer of a meltblown web, a bonded carded web, or othersuitable material. For example, the nonwoven web may be a multilayer webhaving a first layer of spunbonded polypropylene having a basis weightfrom about 0.2 to about 8 ounces per square yard, a layer of meltblownpolypropylene having a basis weight from about 0.2 to about 4 ounces persquare yard, and a second layer of spunbonded polypropylene having abasis weight from about 0.2 to about 8 ounces per square yard.Alternatively, the nonwoven web may be a single layer of material, suchas, for example, a spunbonded web having a basis weight from about 0.2to about 10 ounces per square yard or a meltblown web having a basisweight from about 0.2 to about 8 ounces per square yard.

The nonwoven web outer layers may also be a composite made up of amixture of two or more different fibers or a mixture of fibers andparticles. Such mixtures may be formed by adding fibers and/orparticulates to the gas stream in which meltblown fibers or spunbondfibers are carried so that an intimate entangled co-mingling of fibersand other materials, e.g., wood pulp, staple fibers and particles occursprior to collection of the fibers.

Prior to processing by the method of the present invention, the nonwovenweb outer cover of fibers can be joined by bonding to form a coherentweb structure. Suitable bonding techniques include, but are not limitedto, chemical bonding, thermobonding, such as point calendering,hydroentangling, and needling.

Referring to FIGS. 9 and 10, the nonwoven thermal bond rollerarrangement 108 preferably comprises a patterned calendar roller 110 anda smooth anvil roller 112. One or both of the patterned calendar roller110 and the smooth anvil roller 112 may be heated and the temperature ofeither roller and the pressure between the two rollers may be adjustedby well known means to provide the desired temperature, if any, andpressure to concurrently displace central layer 30 at melt bond sites,and melt bond the two outer layers together at a plurality of bondsites.

The patterned calendar roller 110 is configured to have a circularcylindrical surface 114, and a plurality of protuberances or patternelements 116 which extend outwardly from surface 114. The protuberances116 are disposed in a predetermined pattern with each protuberance 116being configured and disposed to displace central layer 30 at melt bondsites, and melt bond the two outer layers together at a plurality oflocations. One pattern of protuberances is shown schematically in FIG.11. As shown, the protuberances 116 have a relatively small width, WP,which can be between about 0.003 inches and 0.020 inches, but in apreferred embodiment is about 0.010 inches. Protuberances can have alength, LP, of between about 0.030 inches and about 0.200 inches, and ina preferred embodiment has a length of about 0.100 inches. In apreferred embodiment, the protuberances have an aspect ratio (LP/WP) of10. The pattern shown is a regular repeating pattern of staggeredprotuberances, generally in rows, each separated by a row spacing, RS,of about between about 0.010 inches and about 0.200 inches. In apreferred embodiment, row spacing RS is about 0.060 inches. Theprotuberances can be spaced apart within a row by a protuberancespacing, PS generally equal to the protuberance length, LP. But thespacing and pattern can be varied in any way depending on the endproduct desired.

As shown in FIG. 10, patterned calendar roller 110 can have a repeatingpattern of protuberances 116 which extend about the entire circumferenceof surface 114. Alternatively, the protuberances 116 may extend around aportion, or portions of the circumference of surface 114. Likewise, theprotuberances 116 may be in a non-repeating pattern, or in a repeatingpattern of randomly oriented protuberances. Of course, if randomlyoriented, the opening of the resulting bond sites into apertures willalso be somewhat random, depending on the orientation of the bond sitewith respect to the direction of tension, as discussed below. Forexample, if the web is tensioned in the cross-direction (CD) directiononly, then the bond sites 50 having a longitudinal axis 1 with a vectorcomponent in the machine direction (MD) will open into an aperture, atleast to the degree of the magnitude of such a vector component.

The protuberances 116 are preferably truncated conical shapes whichextend radially outwardly from surface 114 and which have rectangular orsomewhat elliptical distal end surfaces 117. Although it is not intendedto thereby limit the scope of the present invention to protuberances ofonly this configuration, it is currently believed that the high aspectratio of the melt bond site 50 is only achievable if the protuberanceslikewise have a narrow width and a high aspect ratio at the distal endsurfaces 117, as shown above with reference to FIG. 11. The roller 110is preferably finished so that all of the end surfaces 117 lie in animaginary right circular cylinder which is coaxial with respect to theaxis of rotation of roller 110.

The height of the protuberances should be selected according to thethickness of the laminate being bonded. In general, the height dimensionshould be greater than the maximum thickness of the laminate web duringthe calendaring process, so that adequate bonding occurs at the bondsites, and only at the bond sites.

Anvil roller 112, is preferably a smooth surfaced, right circularcylinder of steel.

After passing through nip 106, the three (or more) component webs 120,130, and 140, shown together as web 102 in FIG. 10, have been formedinto unitary laminate web 10. At this point in the process the outerlayers are thermally bonded to each other and unapertured, as shown inFIGs. 1 and 2. Central layer(s) 30, from web 130, is apertured, havingbeen displaced by protuberances 116 in nip 106. Depending on the centrallayer(s) used, it (they) may or may not participate in the bonding aboutthe periphery of the bond sites. In some instances, particularly fornon-thermoplastic, non-fibrous materials, central layer may not beinvolved in the bonding of the outer layers at all. However, forthermoplastic materials, and fibrous materials, some involvement of thecentral layer(s) is observed.

The laminate web 10 may be further processed to form apertures in thewhole laminate web (or portions thereof) by extending portions of theweb in a direction orthogonal to the axis I of bond sites 50. As shownin FIGS. 9 and 10, the axis 1 is generally parallel to the machinedirection MD of the web being processed. Therefore, extension in thecross-direction CD at the bonded portions causes the bond sites 50 torupture and open to form apertures in the web.

One method for forming apertures across the web is to pass the webthrough nip 131 formed by an incremental stretching system 132 employingopposed pressure applicators 134 and 136 having three-dimensionalsurfaces which at least to a degree are complementary to one another.Stretching of the laminate web may be accomplished by other methodsknown in the art, including tentoring, or even by hand. However, toachieve even strain levels across the web, and especially if localizedstrain differentials are desired, the incremental stretching systemdisclosed herein is preferred.

Referring now to FIG. 12, there is shown a fragmentary enlarged view ofthe incremental stretching system 132 comprising incremental stretchingrollers 134 and 136. The incremental stretching roller 134 includes aplurality of teeth 160 and corresponding grooves 161 which extend aboutthe entire circumference of roller 134. Incremental stretching roller136 includes a plurality of teeth 162 and a plurality of correspondinggrooves 163. The teeth 160 on roller 134 intermesh with or engage thegrooves 163 on roller 136, while the teeth 162 on roller 136 intermeshwith or engage the grooves 161 on roller 134. The teeth of each rollerare generally triangular-shaped, as shown in FIG. 13. The apex of theteeth may be slightly rounded, if desired for certain effects in thefinished web.

FIG. 13, shows a portion of the intermeshing of the teeth 160 and 162 ofrollers 134 and 136, respectively. The term “pitch”as used herein,refers to the distance between the apexes of adjacent teeth. The pitchcan be between about 0.02 to about 0.30 inches, and is preferablybetween about 0.05 and about 0.15 inches. The height (or depth) of theteeth is measured from the base of the tooth to the apex of the tooth,and is preferably equal for all teeth. The height of the teeth can bebetween about 0.10 inches and 0.90 inches, and is preferably about 0.25inches and 0.50 inches.

The teeth 160 in one roll can be offset by one-half the pitch from theteeth 162 in the other roll, such that the teeth of one roll (e.g.,teeth 160) mesh in the valley (e.g., valley 163) between teeth in themating roll. The offset permits intermeshing of the two rollers when therollers are “engaged” or in an intermeshing, operative position relativeto one another. In a preferred embodiment, the teeth of the respectiverollers are only partially intermeshing. The degree to which the teethon the opposing rolls intermesh is referred to herein as the “depth ofengagement” or “DOE” of the teeth. As shown in FIG. 13, the DOE, E, isthe distance between a position designated by plane P1 where the apexesof the teeth on the respective rolls are in the same plane (0%engagement) to a position designated by plane P2 where the apexes of theteeth of one roll extend inward beyond the plane P1 toward the valley onthe opposing roll. The optimum or effective DOE for particular laminatewebs is dependent upon the height and the pitch of the teeth and thematerials of the web.

In other embodiments the teeth of the mating rolls need not be alignedwith the valleys of the opposing rolls. That is, the teeth may be out ofphase with the valleys to some degree, ranging from slightly offset togreatly offset.

As the laminate web 10 having melt bonded locations 50 passes throughthe incremental stretching system 132 the laminate web 10 can besubjected to tensioning in the CD or cross-machine direction causing thelaminate web 10 to be extended in the CD direction. Alternatively, oradditionally, the laminate web 10 may be tensioned in the MD (machinedirection). The tensioning force placed on the laminate web 10 can beadjusted (e.g., by adjusting DOE) such that it causes the melt bondedlocations 50 to separate or rupture creating a plurality of apertures 60coincident with the melt bonded locations 50 in the laminate web 10.However, portions of the melt bonds of the laminate web 10 remain, asindicated by portions 62 in FIG. 4, thereby maintaining the laminate webin a coherent, unitary web condition even after the melt bondedlocations rupture.

After being subjected to the tensioning force applied by the incrementalstretching system 132, the laminate web 10 includes a plurality ofapertures 60 which are coincident with the melt bonded regions 50 of thelaminate web. As mentioned, a portion of the circumferential edges ofapertures 60 include remnants 62 of the melt bonded locations 60. It isbelieved that the remnants 60 help to resist further tearing ordelamination of the laminate web. Remnants 62 may also contain portionsof central layer 30, to the extent that the central layer is involved inthe bonding.

Instead of two substantially identical rolls 134 and 136, one or bothrolls can be modified to produce extension and additional patterning.For example, one or both rolls can be modified to have cut into theteeth several evenly-spaced thin channels 246 on the surface of theroll, as shown on roll 236 in FIG. 14. In FIG. 14 there is shown anenlarged view of an alternative incremental stretching system 232comprising incremental stretching rollers 234 and 236. The incrementalstretching roller 234 includes a plurality of teeth 260 andcorresponding grooves 261 which extend about the entire circumference ofroller 234. Incremental stretching roller 236 includes a plurality ofteeth 262 and a plurality of corresponding grooves 263. The teeth 260 onroller 234 intermesh with or engage the grooves 263 on roller 236, whilethe teeth 262 on roller 236 intermesh with or engage the grooves 261 onroller 234. The teeth on one or both rollers can have channels 246formed, such as by machining, such that regions of undeformed laminateweb material may remain after stretching. A suitable pattern roll isdescribed in U.S. Pat. No. 5,518,801, issued May 21, 1996, in the nameof Chappell, et al., the disclosure of which is incorporated herein byreference.

Likewise, the incremental stretching can be by mating rolls oriented asshown in FIG. 15. Such rolls comprise a series of ridges 360, 362, andvalleys, 361, 363 that run parallel to the axis, A, of the roll, either334 or 336, respectively. The ridges form a plurality oftriangular-shaped teeth on the surface of the roll. Either or both rollsmay also have a series of spaced-apart channels 346 that are orientedaround the circumference of the cylindrical roll. Rolls as shown areeffective in incrementally stretching a laminate web 10 in the machinedirection, MD if the axis 1 of bond sites 50 is oriented generallyparallel to the cross-machine, CD direction of the web as its beingprocessed.

In one embodiment, the method of the present invention can comprise bothCD and MD incremental stretching. As shown in FIG. 16, two pairs ofincremental stretching rolls can be used in line, such that one pair(232, which, as shown in FIG. 16 includes a series of spaced-apartchannels 246) performs CD stretching, and another pair, 332 performs MDstretching. By this method many interesting fabric-like textures can bemade. The resulting hand and visual appearance make such fabric-likewebs ideal for use in articles benefiting from a fabric-like look andfeel. For example, if a central layer 30 comprises a material havingless elongation to break than either outer layer, and is stretched tofailure in both the CD and MD directions by the method described herein,the resulting laminate web 10 exhibits “islands” of central layermaterial. The islands are discrete, non-continuous portions of centrallayer, and give the laminate web 10 a decidedly fabric-like look andfeel. In this manner, if a metal foil is used as a central layer 30between two relatively translucent materials, such as low basis weightnonwovens, the resulting laminate web 10 resembles a sequined fabric.

The use of rather brittle, or relatively still materials can be used asa central layer 30 with beneficial results when the laminate web isincrementally stretched as described herein. For example, thin ceramicmaterials having a relatively high stiffness can be used as centrallayer 30 in a laminate web 10 that is relatively highly flexible in atleast one direction, depending on the direction of stretch. Therefore,if the web is incrementally stretched in the CD direction, the laminateweb will be flexible about an axis parallel with the MD direction, andvice-versa. If the web is incrementally stretched in both directions,then the resulting laminate web 10 will be relatively highly flexibleabout two axes, and, depending on the size of the discrete “islands” ofcentral layer produced, approaches the overall flexibility of the twoouter layers.

EXAMPLES

The following examples are shown in Table 1 as exemplary of the claimedinvention. Because the choice of outer and inner layers and combinationsis virtually infinite, the examples shown are meant to be illustrativeof possible structures, and are not meant to be limiting to anyparticular material or structure. In particular, the examples shown arelimited to currently preferred structures comprising nonwoven webs asthe outer layers.

In Table 1 various combinations of materials are shown. The layers arenumbered in order of structural proximity from one outer layer to theother. Therefore, layer 1 is always an outer layer, and the lastnumbered layer is likewise an outer layer.

For all the samples shown, the calendaring line speed was 100 feet perminute, but the line speed is not considered critical to the operationof the method. The calendaring pressure was 700 psig for all thesamples, but the pressure can be varied as desired as long as bonding isachieved between the outer layers.

To form apertured embodiments of the samples below, the thermally bondedlaminate was processed by the incremental stretching process asdescribed above with reference to FIG. 12. For these samples a “pitch”and depth of engagement (“DOE”) are shown.

Clopay PE films were obtained from Clopay, Cincinnati, Ohio These thin(about 0.001″ thick) films are a soft and deformable polyethylene type,often used as fluid barrier materials for absorbent products.

Tredegar elastomeric formed films were obtained from Tredegar FilmProducts, Terre Haute, Ind. By “formed film” is meant amacroscopically-expanded three-dimensional plastic web comprising acontinuum of capillary networks originating in and extending from onesurface of the web and terminating in the form of apertures in theopposite surface thereof. Such a formed film is disclosed in commonlyassigned U.S. Pat. No. 4,342,314 issued to Radel et al. on Aug. 3, 1982.Elastomeric formed films are an improvement in the aforementioned Radelet al. web as disclosed in the above-mentioned commonly assigned,copending U.S. patent application Ser. No. 08/816,106 entitled TearResistant Porous Extensible Web, filed Mar. 14, 1997 in the name ofCurro et al. Curro '106 discloses elasticized polymeric webs generallyin accordance with the aforementioned Radel et al. Patent that may beproduced from elastomeric materials known in the art, and may belaminates of polymeric materials. Laminates of this type can be preparedby coextrusion of elastomeric materials and less elastic skin layers andmay be used in the body hugging portions of absorbent garments, such asthe waistband portions and leg cuffs.

High internal phase emulsion open cell foam materials can be madegenerally in dance with the teachings of the above mentioned U.S. Pat.Nos. 5,260,345 and U.S. Pat. No. 5,268,224.

BBA and Corovin/BBA nonwovens were obtained form BBA, Greenville, S.C.

BOUNTY® paper towels were obtained from The Procter & Gamble Co.,Cincinnati, Ohio.

REYNOLD'S metal foil products were obtained from Reynold's MetalProducts company.

3M products were obtained from 3M, Minneapolis, Minn.

For the materials shown below, the basis weight is expressed in gramsper square meter (gsm). Low density polyethylene is denoted “LDPE”;polypropylene is denoted as “PP”; and polyethylene is denoted as “PE”.Spunbond is denoted as “SB”.

TABLE 1 Examples of Laminate Webs of the Present Invention Roller Temp.Anvil/ Pitch/ Exam- Pattern DOE ple No. Layer 1 Layer 2 Layer 3 Layer 4Layer 5 (deg. F.) (inches) 1 30 gsm LDPE 42 gsm 30 gsm LDPE 250/270 SBnonwoven BOUNTY ® SB nonwoven from Paper Towel from Corovin/BBACorovin/BBA 2 30 gsm LDPE 42 gsm 42 gsm 30 gsm LDPE 250/270 0.200/ SBnonwoven BOUNTY ® BOUNTY ® SB nonwoven 0.300 from Paper Towel PaperTowel from Corovin/BBA Corovin/BBA 3 30 gsm LDPE 42 gsm 30 gsm LDPE250/270 0.060/ SB nonwoven BOUNTY ® SB nonwoven 0.850 from Paper Towelfrom Corovin/BBA Corovin/BBA 4 80/20 (PE/ 23 gsm PE 50/50 (PE/ 275/295PP) 30 gsm film from PP) 30 gsm SB nonwoven Clopay SB nonwoven from BBAfrom BBA 5 80/20 (PE/ 23 gsm PE 50/50 (PE/ 275/295 0.200/ PP) 30 gsmfilm from PP) 30 gsm 0.300 SB nonwoven Clopay SB nonwoven from BBA fromBBA 6 80/20 (PE/ 42 gsm 23 gsm PE 50/50 (PE/ 275/295 PP) 30 gsm BOUNTY ®film from PP) 30 gsm SB nonwoven Paper Towel Clopay SB nonwoven from BBAfrom BBA 7 80/20 (PE/ 42 gsm 23 gsm PE 50/50 (PE/ 275/295 0.200/ PP) 30gsm BOUNTY ® film from PP) 30 gsm 0.300 SB nonwoven Paper Towel ClopaySB nonwoven from BBA from BBA 8 30 gsm LDPE M77 spray REYNOLDS ® M77spray 30 gsm LDPE 275/295 0.060/ SB nonwoven adhesive from 65 gsmadhesive from SB nonwoven 0.850 from 3M aluminum foil 3M fromCorovin/BBA approx. 13 approx. 13 Corovin/BBA gsm gsm 9 30 gsm LDPE 88gsm 42 gsm 30 gsm LDPE 250/270 0.200/ SB nonwoven elastomeric BOUNTY ®SB nonwoven 0.300 from formed film Paper Towel from Corovin/BBA fromTredegar Corovin/BBA 10 30 gsm LDPE Spray hot 62 gsm High Spray hot 30gsm LDPE 250/270 0.200/ SB nonwoven melt adhesive Internal Phase meltadhesive SB nonwoven 0.300 from from Ato- Emulsion from Ato- fromCorovin/BBA Findley open cell Findley Corovin/BBA approx. 12 foamapprox. 12 gsm gsm 11 27 gsm high 42 gsm 60 gsm 295/350 0.060/elongation BOUNTY ® laminate of 0.110 carded PP Paper Towel 80/20 50/50nonwoven (PE/PP) from BBA nonwoven from BBA

The laminate webs of the present invention may be utilized in manyvaried applications. For example, the relatively low cost of nonwoven,paper and film materials makes the laminates ideally suited fordisposable articles. The articles discussed herein are exemplary of theuseful applications for which the laminate of the present invention canbe used.

FIG. 17 shows an exemplary embodiment of a disposable diaper 420 in aflat configuration (with all elastic induced contraction removed) withportions of the structure being cut-away to more clearly show theconstruction. The portion of the diaper which contacts the wearer facesthe viewer. The diaper is preferably comprises a liquid pervioustopsheet 438; a liquid impervious backsheet 440 joined with the topsheet438; an absorbent core 442 (shown as an apertured laminate of thepresent invention) positioned between the topsheet 438 and the backsheet440; elastic members 444; and tape tab (or mechanical) fasteners 446.The components can be assembled in a variety of well knownconfigurations.

Liquid pervious topsheet 438 could be made of a laminate web likeExample 4 (unapertured) or Example 5 (apertured) as shown in Table 1.Backsheet 440 could be made of a laminate webs like Example 4, andabsorbent core 442 could be made of a laminate like that of Example 10.Side panels, elastic leg cuffs, and an elastic waist feature can be madeof a laminate web like Example 9. Such a laminate exhibits breathabilityand elasticity, both important in absorbent diapers.

A preferred diaper configuration for a diaper comprising laminates ofthe present invention is described generally in U.S. Pat. No. 3,860,003,issued Jan. 14, 1975 to Buell. Alternatively preferred configurationsfor disposable diapers are also disclosed in U.S. Pat. Nos. 4,808,178(Aziz et al.); 4,695,278 (Lawson); 4,816,025 (Foreman); 5,151,092 (Buellet al.), all of which are hereby incorporated herein by reference.

In addition to disposable diapers, various embodiments of laminates ofthe present invention are useful for topsheets, backsheets, and cores inother disposable absorbent articles, such as catamenials, panty liners,pull-up diapers, adult incontinence products, and the like.

Laminates of the present invention can also be useful as wipes,including wet wipes, shop wipes, facial wipes, and the like. Forexample, Example 3 having an absorbent cellulosic layer as central layer30 would be an excellent wipe for picking up spills and particulatematter that can be captured in the apertures. Likewise, Example 6,having a polyethylene film would be an excellent wipe for harsh jobsrequiring a more durable wipe having extra scrubbing capability. Alaminate of the present invention can be considered a durable orsemi-durable rag or sponge for most purposes.

Because of the virtually infinite variety of patterns achievable by themethod of the present invention, laminates of the present invention canfind use as components in home furnishings, including drapes andupholstery. For example, very lacy, sheer patterns can be made that areattractive as window coverings. The colors can be varied easily byvarying the component materials, including central layer 30. Higherbasis weight materials can be made durable for seat coverings,particularly disposable seat coverings useful in airplanes, buses, andthe like.

Laminates of the present invention can be useful as disposable bibs.Example 6 in Table 1, for example, having a polyethylene layer wouldserve as an effective bib. Even apertured versions, depending on thesize of the apertures can be useful as bibs, as the apertures tend tocapture food particles better. After use as a bib the bib can be used asa wipe to clean up the baby's surroundings after eating.

Metal-containing webs of the present invention can be used in electricalapplications. For example, Example 8 in Table 1 can be used inapplications requiring electrical shielding having a soft, compliantcarrier material. A laminate similar to Example 8 may find use as acomponent in circuit boards, electrical cabling, and the like.

A laminate web of the present invention can find use as a filter forfiltering fluids. Air, for example, can be filtered in passing airthrough a suitably designed laminate web of the present invention. Forexample, electrostatic air filters can be made by laminating appropriatedissimilar polymeric nonwoven materials. In one embodiment the filterwould comprise nonwoven materials of suitable material and pore size,and would be provided in an unstretched condition, that is, in alaminate such as that shown with respect to FIGS. 1 and 2. As the filteris used, and the pores become blocked with filtered debris, the tensionplaced on the filter media thereby would cause at least some of the bondsites 50 to open into apertures. Thus, the filter comprises a selfadjusting media that prevents complete blockage of the filter, andavoids overworking of blower motors and the like.

Other uses for laminates of the present invention include medicaldressings, textured wall coverings, mats and throws, mop heads for dryor wet mops, and geo-textiles.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. A non-apertured laminate web comprising: a) a first web; b) a secondweb joined to said first web in a face to face relationship at aplurality of discrete bond sites, the first and second webs forming aninterior region therebetween; c) a third material being disposed betweensaid first and second webs, said third material being differentiatedfrom said first or second web by at least one material property selectedfrom thermal properties, elongation properties, elastic properties, orconductive properties; and d) said third material being apertured inregions coincident said bond sites; such that said first and second websare joined through said apertures and wherein said third materialisinvolved in said discrete bond sites and substantially fills saidinterior region.
 2. The laminate web of claim 1, wherein said laminateis joined by bonds in the absence of adhesive.
 3. The laminate web ofclaim 1, wherein said bond sites are discrete thermal bonds having anaspect ratio of at least 3:1.
 4. The laminate web of claim 1, whereinsaid bond sites are discrete thermal bonds having an aspect ratio of atleast 10:1.
 5. The laminate web of claim 1, wherein said first or secondweb comprises a nonwoven.
 6. The laminate web of claim 1, wherein saidthird material comprises cellulosic tissue paper.
 7. The laminate web ofclaim 1, wherein said third material comprises metal foil.
 8. Thelaminate web of claim 1, wherein said third material is a polymericfilm.
 9. The laminate web of claim 1, wherein said third material isopen cell foam.